The major effort during the last twelve months has been expanded toward determining the complete amino acid sequence of the induced anti-phenylarsonate antibodies bearing a cross-reactive idiotype. At the time of writing this report, virtually the entire heavy chain has been complete to add to the light chain sequences that were available during the time of writing last year's progress report. Within a few months we anticipate this complete V-region domain to be sequenced and this will represent the first time that an induced antibody which is idiotypically defined, raised in a single inbred animal has been completely sequenced. In addition, several projects involving structural studies on myeloma proteins in animals have been completed. The variable region of a canine kappa chain has been completely sequenced and is in press as well as the total sequence of a canine IgM heavy chain.